Question

Assume we have a cell which contains nonpermeating molecules (p; not ionized) at a concentration of 300 mM/l cell water. Assume the initial cell volume is 1.0nanoliter. What will be the final (i.e. equilibrium) volume when the cell is immersed in a large volume of the following solutions?

A) 300 mOsm sucrose (sucrose cannot penetrate the membrane)

B) 150 mOsm sucrose

C) 600 mOsm sucrose

D) 300 mOsm glycerol (glycerol can penetrate the membrane)

E) pure water

F) 600 mOsm glycerol

G) 300 mOsm sucrose & 300 mOsm glycerol

Please explain work. Label each test solution in terms of its osmolarity and tonicity.

What would the time course of volume change curve (graph Volume vs. time) for solution G look like?

Now assume that the normal Na+ and K+ concentrations of ICF and ECF are as given below, and that the man suffers a severe heart attack, which can cause his cells to lose a little K+ and gain a little Na+:

Na+ (mM/l)

ICF: 10 ECF: 140

K+ (mM/l)

ICF: 145 ECF: 5

After heart attack:

Na+ ICF: 14

K+ ICF: 141

Specifically, assume that the 4mM/l K+ los from the cells is exactly balanced by a gain of Na+. Thus, no other significant fluxes occur. What will be the ECF concentrations of Na+ and K+?